timtinkers.online
posts "question of the day" to a discord webhook
testing a mutex/lock to prevent double posts with Deploy?
+21
-16
+21
-16
main.ts
+21
-16
main.ts
···
10
10
11
11
Deno.cron("QOTD", Deno.env.get("CRON_STRING")!, async () => {
12
12
const date = Temporal.Now.plainDateISO();
13
+
14
+
const kv = await Deno.openKv();
15
+
16
+
// Use today's date string as a unique key for this run
17
+
const lockKey = ["cron_lock", date.toString()];
18
+
const existingLock = await kv.get(lockKey);
19
+
20
+
const lockResult = await kv.atomic()
21
+
.check(existingLock) // only succeeds if the key hasn't changed
22
+
.set(lockKey, true, { expireIn: 60_000 }) // auto-expire after 1 min
23
+
.commit();
24
+
25
+
if (!lockResult.ok) {
26
+
console.log("Another instance already claimed this cron run, skipping");
27
+
return;
28
+
}
29
+
13
30
const { themes, questions } = await fetchData();
14
31
const available = getAvailableThemes(date, themes);
15
32
const { themeName, theme, question } = await drawNextQuestion(
···
17
34
questions,
18
35
);
19
36
20
-
await sendDiscordNotification(
21
-
question,
22
-
theme,
23
-
themeName,
24
-
);
37
+
await sendDiscordNotification(question, theme, themeName);
25
38
console.log(
26
39
`Cron: posted ${themeName} question of index ${theme.index} to Discord.`,
27
40
);
28
-
29
-
// @ts-ignore Deno.openKv is unstable, run with --unstable-kv flag
30
-
const kv = await Deno.openKv();
41
+
31
42
const current = await kv.get<number>([theme.kvKey]);
32
43
const index = current.value ?? 0;
33
44
const nextIndex = (index + 1) % theme.questionCount!;
34
45
35
-
// Perform atomic operation to update index
36
-
const result = await kv.atomic()
37
-
.check(current) // Ensure the value hasn't changed
46
+
await kv.atomic()
47
+
.check(current)
38
48
.set([theme.kvKey], nextIndex)
39
49
.commit();
40
-
41
-
if (!result.ok) {
42
-
console.log("Another instance already updated the index, skipping");
43
-
return;
44
-
}
45
50
});